It is silver, maybe not 925 but since it was sand cast there might have been some contamination that got on the surface in some areas. Iron jump ring doesn't seem to be plated. No marks doesn't always mean anything, it could have been made from a small maker. Still a cool find since it was right next to a metal fence, probably why others had missed it.
The park I was at has a path that follows the original path that passed through an old farm field. Sometime in the 1940's they turned it into a baseball diamond. Other BB diamonds in the same park vary in age, couple I had picked up an 1877 sitting liberty 2" in the sand and a few 1906 indian heads. Buffalos I pulled from there are in rough shape and very hard to read.